I think there is a whole forum on bonsai here if you have a look.Actually, since that photo the fuchsia has died from drying out.Otherwise I prune them into shape probably in late winter when they aren't growing, and I fertilize them with worm juice when I think of it. they do seem to flourish with a regular fertilising regime. The small pots need to be checked and watered regularly.

Don't take a cutting from a plant that has taken over a vacant block just because it's free.